Manometer and transducer type systems are widely used for measuring and monitoring hemodynamic pressure in the body of a patient and these devices include a pressure catheter adapted to be implanted in a particular location in the body of the patient, usually in the right atrium of the heart. The catheter is connected to the pressure measuring device by a tube containing pressure-transmitting fluid and the pressure measuring device is supported for vertical adjustment adjacent the patient. It is well known that the pressure measuring device must be maintained at the same vertical level as the catheter in order to obtain accurate pressure measurements.
When the pressure measuring and monitoring system is initially connected to the patient, it is necessary to vertically adjust the level of the pressure measuring device so that it is positioned at the same level as the catheter implanted in the patient. When the patient changes position, for example when the bed is raised or lowered or when the patient moves between reclining and inclined positions, the vertical position of the implanted catheter also changes vertical positions and the pressure measuring device must also be correspondingly raised or lowered to be positioned at the same level as the catheter, in order to continue to accurately measure and monitor the hemodynamic pressure in the body of the patient. Thus, any adjustment in the vertical position of the patient requires that an attendant make a manual vertical adjustment of the pressure measuring device to a corresponding up or down position to insure a continuous accurate pressure reading.
The necessity to maintain the pressure measuring device at the same level as the catheter has long been recognized and various devices have been proposed for manually aligning the pressure measuring device at the same level as the catheter. For example, U.S. Pat. Nos. 3,495,585; 3,590,818; 3,602,214; 3,690,312; 3,636,942; 3,693,612; 3,996,927; 4,135,509; and 4,431,009 disclose devices used to aid the attendant in vertically aligning the pressure measuring device at the same level as the catheter implanted in the patient. However, the devices shown in these prior patents still require that an attendant make a manual adjustment each and every time that the position of the patient is changed and the vertical level of the implanted catheter is changed.
U.S. Pat. No. 4,489,454 also recognizes the importance of maintaining the level of the pressure measuring device, in this case a transducer, at the same level as the heart of the patient in order to obtain accurate readings. This patent attempts to solve this problem by mounting the transducer on the bed so that changes in the vertical position of the bed also raise and lower the vertical level of the transducer. However, the device of this patent must still be manually adjusted when initially connected to the patient so as to be in vertical alignment with the heart of the patient and provides no means for changing the vertical position of the transducer when the position of the patient changes relative to the level of the bed.